During the manufacture and assembly of performance vehicles such as aircraft, a subassembly must be attached to a supporting substrate with a high degree of precision to ensure efficient operation. To assist with precision alignment, one or more reference holes may be molded into, or predrilled through, the subassembly during manufacture. The reference holes in the subassembly are used to identify the location of holes that are to be drilled through the supporting substrate.
To attach the subassembly to the supporting substrate, an edge of the subassembly may be placed in physical contact with an edge of the supporting substrate to ensure the subassembly is properly aligned with the supporting substrate. A drill bit is inserted through the reference hole in the subassembly, and then a hole is drilled through the supporting substrate using the reference hole in the subassembly to properly locate the hole through the supporting substrate. Any remaining holes are then similarly drilled using the reference holes in the subassembly to properly locate the holes in the supporting substrate.
Even though the reference holes through the subassembly are effective in ensuring that the entrance location of each hole drilled through the supporting substrate is correct, maintaining the drill bit exactly perpendicular to the supporting substrate to ensure the proper exit location of each hole is more difficult. For example, if a drill bit is improperly angled 7° away from vertical during drilling through a material that is 2.5″ thick, the hole will exit the material almost 3/16″ away from its correct location.
Assembly personnel may simply attempt to maintain the drill bit in a vertical position without any mechanical aid other than the reference holes through the subassembly, but this method is inaccurate and varies greatly with the attention and experience of individual assembly personnel. A handheld drill block may be used but the drill block may be only slightly larger than the hole to be drilled, and thus manual alignment of the drill block is difficult and misaligned holes is common. Further, the drill may pitch and yaw during drilling, thereby resulting in an oversized hole. Alignment jigs can be effective in assisting with maintaining perpendicularity of the drill bit with a supporting surface. However, alignment jigs are typically customized for the shape, topography, and desired hole location of one particular surface and are thus not functional with surfaces having a different shape, topography, or desired hole location. Further, alignment jigs may rely on proper alignment and stabilization by assembly personnel as the hole is being drilled. Additionally, during the assembly of aircraft or other structures, many different types of subassemblies must be attached to a supporting substrate which would require different alignment jigs of varying designs, and thus the use of customized alignment jigs is not practical.
A tool that assisted with reliably drilling vertical holes through surfaces having different surface shapes and topographies would be desirable.